RAPID: Microbial cycling of Iron and Sulfur in Spring Creek Reservoir, Iron Mountain Mine

2018年7月，卡尔大火烧毁了近23万英亩土地，包括铁山超级基金场地周围的地区，受地雷影响的排水被转移到Spring Creek水库。微生物改变了水库中的水和沉积物的化学性质，并改变了向下游流动的水的质量。今年，雨季的雨水落在烧痕上，预计会造成快速侵蚀，并将额外的沉积物存款到湖中。这个项目将调查污染的沉积物是如何沉积在湖泊中的，以及微生物是如何转化沉积物、孔隙水和水库水的。项目人员将检查流入的沉积物，沉积物中的微生物群落，以及2018/2019季节风暴事件后水库的水质。研究结果将显示微生物活动如何改变Spring Creek水库的沉积物化学和水质，并提供对类似烧毁地区和受地雷影响土壤的见解。美国西部的采矿活动导致数千英里的河流受到酸性矿山排放的影响，以及矿山和冶炼厂作业对土壤的广泛污染。 从铁山矿排放的污染水和沉积物历史上影响了萨克拉门托河上游，这是一个重要的饮用水源和鲑鱼产卵流。该项目的成果将有助于矿山管理人员、地方和区域环境规划人员以及水库管理人员了解再流动沉积物的移动和命运，并就野火对植被和有助于稳定受污染土壤的复垦基础设施的影响进行规划。 铁山超级基金场地包含几个废弃矿山的残留物，Spring Creek通过Spring Creek泥石流坝和水库（SCR）对该区域的部分区域进行排水，在排放物进入凯斯威克水库和萨克拉门托河之前将其捕获。2018年7月，卡尔大火烧毁了春溪流域的大部分地区，因此，预计2018/19雨季的沉积量将很高。沉积物的涌入提供了一个机会，调查微生物群落如何殖民化和改造沉积物和孔隙沃茨在酸性矿山排水影响的湖泊。SCR中的先前研究表明，在高水库水位期间，微生物群落减少孔隙沃茨中的铁和硫酸盐，并且当水位低时，铁和硫化物氧化，产生酸性并使金属流动。 拟议的研究将表征沉积物流入，微生物群落如何在新的沉积物中发展，以及微生物活动如何改变孔隙水化学。研究团队将于2018年11月至2019年对沉积物和孔隙水及地表水进行8次采样分析。分析将包括矿物学;铁，硫，氧和水的pH值;和微生物群落的分子分析。这项研究将为酸性矿山排水污染环境中的环境地球化学提供基本见解，并为SCR中的水质管理提供指导。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

In July 2018, the Carr Fire burned nearly 230,000 acres, including the area surrounding the Iron Mountain Superfund Site where mine-impacted drainage is diverted into the Spring Creek Reservoir. Microbes alter the water and sediment chemistry in the reservoir and change the quality of the water flowing downstream. This year, rain falling on the burn scar during the wet season is expected to cause rapid erosion and deposit extra sediment into the lake. This project will investigate how contaminated sediments are deposited in the lakes, and how microbes transform sediment, pore water, and reservoir water. Project personnel will examine inflowing sediments, microbial communities from the sediment, as well as water quality in the reservoir following storm events in the 2018/2019 season. Results will show how microbial activity changes sediment chemistry and water quality in the Spring Creek Reservoir and provide insights into similar burned over areas and mine-impacted soils. Mining activities in the Western USA has resulted in thousands of miles of streams impacted by acid mine discharge, and widespread contamination of soils by mine and smelter operations. Discharge of contaminated water and sediment from the Iron Mountain mine has historically impacted the upper Sacramento River, an important drinking water source and salmon spawning stream. The results of this project will help mine managers, local and regional environmental planners and reservoir managers understand the movement and fate of remobilized sediments, and to plan for the effects of wildfire on the vegetation and reclamation infrastructure that help to stabilize contaminated soils. The Iron Mountain Superfund Site contains the remnants of several abandoned mines, and Spring Creek drains part of this area with the Spring Creek Debris Dam and reservoir (SCR) capturing discharge before it enters the Keswick Reservoir and Sacramento River. In July 2018, the Carr Fire burned most of the Spring Creek watershed, and thus, sedimentation is expected to be high during the 2018/19 rainy season. The influx of sediment provides an opportunity to investigate how microbial communities colonize and transform sediment and pore waters in an acid mine drainage-influenced lake. Prior research in the SCR suggests that microbial communities reduce iron and sulfate in pore waters during high reservoir levels, and that iron and sulfide oxidize when water levels are low, producing acidity and mobilizing metals. The proposed research will characterize sediment influx, how microbial communities develop within the new sediment, and how microbial activity changes pore water chemistry. The research team will sample and analyze the sediments and pore and surface water 8 times from November 2018 to 2019. Analyses will include mineralogy; iron, sulfur, oxygen, and pH of the water; and molecular analyses of the microbial communities. This research will provide fundamental insights into environmental biogeochemistry in acid mine drainage-contaminated environments and provide guidance for managing the water quality in the SCR.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.